Liquid heater



July 8 l924.-

H. JUNKERS LIQUID HEATER /T' 0 filed June 29. 1920 2 Sheets-Sheet' 1 .my e, 1924; 1,500,456

H. JUNKERS LIQUID HEATER Filed June 29. 1920 2 Sheets-Sheet 2 IIN: "HHHHIH llll :uw l Ill iHH,

Patented July e, 1924.

HUGO JUNXERS, OF DESSAU, G

LIQUID EEATER.

` Application led J'une 29, 1920. Serial Fo. 892,887.

To all whom it may concern.'

Be it known that I, HUGO JUNKERS, a citizen of the German Empire, 4residing at Dessau, Germany, have invented certain new 5 and useful Improvements in Liquid Heaters,

vof which the following is a spec1fication.

My invention relates to appliances in which combustion gases are led along cooled metal partitions such as heaters for liquids,

.10 steam generators etc. with a cooled shaft or flue for the rising combustion gases. The appliances of this kind hitherto known involve the drawback that on account of the inuence of the radiation-of the shaft walls their temperature at the side touching the gases was lower than the dew point of the combustion gases so that the moisture of these gases condensed upon the inner Wall of the shaft. Experience shows that this l0 condensation assists to a very great extent the combustion gases in their chemical. influence upon the shaft Walls and is the cause of their early destruction.

Itl has been proposed to prevent the condensation of water by coating the/ cooled walls exposed to the combustion gases with a material of lesser`thermal conductivity. This however involves several disadvantages; the material suitable for such coating (e. g. asbestos) has very little strength and is easily damaged for this reason. Therefore special precautions must be taken to rotect it. Besides it is diicult to fasten suc a coating on the walls of a liquid heater. Inasmuch as inaddition to all vthis such a coating acts as a non-conducting material the heating effect of. the cooled wall is considerably reduced.

. According to the present invention, now,

40 the condensation on the cooled walls vis avoided by arranging another metal wall facing the combustlon gases at a certain distance from the wall to be protected; this wall is connected with the protected wall at certain intervals byl a heat conductor. The effect of this arrangement can be concluded from the following: if the Wall be unprotected the heat of the combustion gases is transmitted everywhere through the wall into the liquid, i. e. it has to overcome only the comparatively small thermal resistance of the wall depending upon its thickness, so that only a smalldrop of temperature is caused. With the arrangement according to my invention on the other hand the heat transmitted to the protecting Wall has to be conveyed therein a considerable length of .Way until it is transmitted at the points where the protectin wall and the main wall are connected into't e latter and from there 60 in'to the liquid. For this reason, i. e. owing to the longer distance to be traversed by the heat, a greater difference in temperature is necessary, i. e.. the protecting wall will be hotter than the wall to be protected. As the 05 entire heat entering the protecting wall must flow throu h the comparatively small places of contact etween the walls, in these places an especially powerful fiow of heat results which cannot be maintained but by a greater drop in temperature, so that also in these places the temperature of the walls will be considerably higher on the side facing the gases than in cooled shaft walls directly exposed to the heating gases. Provision can be made either by experiments or calculation that the drop in temperature required for transmitting the heat from the protecting wall to the liquid becomes so 'high that the temperature of the protecting wall is higher so than the dew point of the heating gases.

lThus the protecting wall remains perfectly dry and is protected from thefchemical influences of the gases. On the other hand the temperature of this protecting wall cannot become unduly high as the heat transmitted into the protecting wall is conducted through the points of connection into the protected wall and from there into the cooling medium touching it. In order to ensure an exact regulation of the temperature of the protecting wall in those places Where the cooling medium still has a lowerl temperature, the points of contact may be arranged at a greater distance from each other, so that the way traversed by the heat in the protecting wall increases and that the difference of temperature between the latter and the cooling medium is greater than in those places where the cooling medium has a higher temperature.

As now the rotected wall is not touched any more byvt e gases no moisture can settle on it.

In order to ensure this absolutely and to 1w prevent the combustion gases from enterin the small. interstice between protecting an protected wall the arrangement may be ful ther improved by closing this interstice at the of the protecting wall.

In t e drawings aixed to this specification and forming part thereof several modiications of a 1i uid heater embodym my invention are i ustrated by way o exam le. In the drawings- IPig. 1 is a vertical section following line I-I in Fig. 2,

Fi 2 a horizontal section on the line II- I in Fig. 1,

Figs. 3 to 8 show various details,

Fig. 9 `illustrates another modification.

The heater consists of an annular tank confined' by the innerwall 1 and the outer wall 2. At the lower end of this tank a burner 3 is placed. The heatingt gases ow at first through an emplty sha 5 formed bythe lower part of t e heater and then enter the radiator 4 in which they lose most of their heat. They leave the heater throu h the top opening of the cap 6. Inside 51e shaft 5 at a small distance from the inner wall 1 of the tank another wall, the protecting wall 7, is arranged which consists equally of metal. The protecting wall has vertical grooves 8 whose back faces are thermally connected with the cooled wall 1. The top end of wall 7 at 9 is bent back in the direction of wall 1 so as to prevent the gases from entering the interst-ice between the walls 1 and 7.

This space may of course be closed in any other way, e. g. by insertin a cordV 10 of material able 'to withstan the heat, as shown in Fig. 3.

The construction of the connecting places between the cooled wall 1 and the protecting wall 7 can'be carried out differently. Instead of the vertical grooves horizontal ones might be arranged. A further modification is shown in Figs. 4 and 5. Here the protecting wall 7 has saucer-like indenta' tions whose back faces are connected with the cooled wall 1.

The projections, grooves etc. connecting both walls may of course be provided also in the cooled wall 1.

For transmitting the heat from the protecting wall 7 'to wall 1 separate intermediate bodies may be arranged which are thermally connected with both walls. An example is to be seen in Fig. 6, here a third corrugated wall is inserted between walls 1 and 7 transmitting the heat from wall 7 to wall 1.

The thermal connection between protecting and cooled wall can be accomplished in some way or other, such as by soldering, welding or by mere pressure. A modification of the last-named type may be seen in Fig. 7,'- here the protecting wall 7 of a cylindrical iue is dissolved into separate segment-like arts whose ends are rovided with s ort bends 15, which ean against wall 1. By the sing-like action of the curved back faces of t e wall parts fitted in under pressure a lasting pressure of the bends 15 against the cooled wall 1 is -ensured.

Fig. 8 shows an example for the adaptation of this invention to a wall 1 which is not cooled continuousl but in zones. The cooling of the wall is one by a liquid contained in pipes which are soldered upon 'wall 1 at certain distances.

The protecting wall is in this case thus connected with wall 1 that. the `portions connecting both walls lie between each twocooling plpes 16. The heat enteringv the protecting wall 7 cannot but flow in this wall to this connecting place and then through wall 1 to the connections ofthe pipes 16 before it reaches the liquid. Through this long Wandering of the heat a temperature of the protectlng wall well above the dew point of the heating gases is obtained with great security.

It has further been ascertained that the condensation does not only take place in the heating shafts but as well on the walls of the intrinsic heat-transmitting appliance. especially in those places where they are not covered with ribs. For this reason it is desirable to cover these parts of the wall with a protecting mantletoo: but its arrangement is mostly very diiicult on account vof the rather complicated construction of such heat-transmitting appliances.

According to the present invention those parts of the heater wall, which are mostly exposed to destruction through condensation, are to beprotected by shaping the radiator ribs nearest to these walls into a protecting wall so that Vseparate protection walls become superiuous.

Fig. 9 is a vertical section of a liquid heater embodying this feature. Here the heat transmitting body oif a heater for liquids is arranged in the upper part of the shaft 21. The liquid which is to be heated pours into the distribution chamber 22 arranged on the one side of the shaft` is led across the stream of heating gases in pipes 23, is recollected in a collection chamber 27 arranged on the other side of the funnel and is from there 'led to their destination. The tubes or channels 23 containing'the liquid are provided. with ribs 24 which run in the direction of the gas current marked by arrows: According to the' ordinary construction of such heat-transmitting appliances the heating gases flow throu h the narrow space between the end r1 s 24 and 24 and the inner walls 25 and 26 of the tanks 22 and 27. As the walls 25 and 26-contrary to the channel walls 23--possess no enlarged surface on the side exposed toA the.v gases, their temperature becomes only very little higher than that of the liquid so that on these walls condensation can take place, especially on wall 25 containing the cooler liquid. According to the present .invention this disadvantage is avoided by shaping the ribs 24 and 24 adjoining these walls into pro tecting walls. For this purpose these ribs as compared to the others, are somewhat elongated in the direction facin the current of heating gases and their ens are connected with the walls 25 and 26, so as to prevent the heating gases rising up in shaft 2l from gettin into the interstices between wall 25 an rib 24 and between wall 26 and rib 24; by this the walls 25 and 26 are protected from condensing moisture. A detrimental overheating of the ribs24 and 24 servi as protecting walls is prevented by t eir thermal connection with the channels 23 containing theliquid.

In those cases where a water-cooled shaft is' used the ribs serving as a protecting mantle may extend directly into the protecting wall of the funnel shaft.

I claim:

1. In apparatus of the kind described in combination, a wall, means for cooling one side of said wall, a protective metal wall disposed near, but spaced apart from the other side of said cooled wall heat-conductive connections between said' walls and means for preventin hot gases from entering from below t e space intermediate said walls.

2. In apparatus of the kind described in combination, a wall, means for cooling one side of said wall, a protective metal wall disposed near, but spaced apart from the other side of said cooled wall, metallic connections between said walls and means for preventing hot gases from entering from below the space intermediate said walls.

3. In a liquid heater in combination, a liquid container of annular section, a pro tective metal wall disposedlnear, but spaced apart from and connected in some places to the inner wall of said container, and connections between the lower portions of said walls for preventing hot gases from entering the space intermediate said walls.

4. In apparatus of the kind described in combination, a wall, means for coolin one side of said wall, a protective metal wa disposed near, but spaced apart from the other v side of said cooled wall, heat-conductive connections between said walls held in contact with the other side of said cooled wall by mere vpressure and means for preventing hot .gases from entering from below the space intermediate said walls.

5. In apparatus of the kind ldescribed in combination, a wall, and ribbed elements disposed at an angle to and operatively connected with said wall, means for cooling one side of said wall and said elements, the ribs adjoining said cooled wall extending along, but spaced apart from said cooling wall so as to form a protective wall.

6. In apparatus of the kind described in combination, a liquid container of annular section, a protective wall surrounded by and substantially concentric with said container, heat-conductive connections betweenn said container and said wall and connections between the lower edges of said container and said wall `for preventing hot/gases from entering the space intermediate sald walls.

In testimony whereof I aiix my slgnature.- 

